JP2022081977A - Optical system and imaging apparatus - Google Patents
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- G—PHYSICS
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- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
- G02B9/60—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having five components only
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/14—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation
- G02B13/146—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation with corrections for use in multiple wavelength bands, such as infrared and visible light, e.g. FLIR systems
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/22—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with movable lens means specially adapted for focusing at close distances
- G02B15/24—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with movable lens means specially adapted for focusing at close distances having a front fixed lens or lens group and two movable lenses or lens groups in front of a fixed lens or lens group
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- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
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- G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
- G02B27/005—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration for correction of secondary colour or higher-order chromatic aberrations
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- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
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Abstract
Description
本件発明は、光学系及び撮像装置に関する。 The present invention relates to an optical system and an image pickup apparatus.
従来より、一眼レフカメラ、デジタルカメラ、ビデオカメラ、監視用カメラの他、産業用カメラ等種々の分野で撮像装置が使用されている。いずれの分野においてもイメージセンサ（撮像素子）の高画素化が進み、それに伴い明るく高解像度の光学系が求められている。近年、産業用カメラ、特に、画像解析装置に接続されて画像解析による検査等に用いられるマシンビジョン用の産業用カメラ（ＦＡ／ＭＶ）の重要性が高まっている。特に、可視光域から近赤外域までの広い波長域の光線により、物体の外部構造だけではなく、その内部等についてもセンシングが可能な産業用カメラが注目されている。このような撮像装置に対しては、可視光域から近赤外域までの広い波長域において良好に収差補正された結像性能の高い光学系が求められる。 Conventionally, image pickup devices have been used in various fields such as single-lens reflex cameras, digital cameras, video cameras, surveillance cameras, and industrial cameras. In all fields, the number of pixels of image sensors (image sensors) is increasing, and along with this, bright and high-resolution optical systems are required. In recent years, the importance of industrial cameras, particularly industrial cameras (FA / MV) for machine vision, which are connected to an image analysis device and used for inspection by image analysis and the like, is increasing. In particular, industrial cameras that can sense not only the external structure of an object but also the inside thereof by means of light rays in a wide wavelength range from the visible light region to the near infrared region are attracting attention. For such an image pickup device, an optical system having high imaging performance in which aberrations are well corrected in a wide wavelength range from the visible light region to the near infrared region is required.
例えば、特許文献１には、物体側より順に負の屈折力を有する第１レンズ群と正の屈折力を有する第２レンズ群とから構成され、Ｆナンバーが１．４程度の明るい光学系が開示されている。
また、特許文献２には、物体側より順に屈折力を有する第１レンズ群と、正の屈折力を有する第２レンズ群とから構成され、Ｆナンバーが２．８程度の比較的明るい光学系が開示されている。
しかしながら、特許文献１及び特許文献２に開示の光学系はいずれも可視光域から近赤外域全域における諸収差の補正が十分であるとはいえない。
For example,
Further,
However, it cannot be said that the optical systems disclosed in
そこで、本件発明の課題は可視光域から近赤外域全域において諸収差が良好に補正された結像性能の高い光学系及び撮像装置を提供することにある。 Therefore, an object of the present invention is to provide an optical system and an image pickup apparatus having high imaging performance in which various aberrations are satisfactorily corrected in the entire visible light region to the near infrared region.
上記課題を解決するために本件発明に係る光学系は、合焦時における最も物体側の可変間隔を挟んで、物体側に配置される屈折力を有する第１レンズ群と、像側に配置される正の屈折力を有する第２レンズ群とから構成され、前記第１レンズ群は、像側から順に、正レンズと、少なくとも１枚以上の負レンズとを含み、前記第２レンズ群は、物体側から順に、正の屈折力を有する第２Ａ群と、開口絞りと、正の屈折力を有する第２Ｂ群とを有し、前記第２Ｂ群は、物体側から順に負レンズと、正レンズとを含み、下記条件式を満足することを特徴とする。
（１） －０．０５０ ＜ θＩＲｐ－θＩＲｎ ＜ ０．０５０
（２） １．５ ＜ Ｆ２／Ｆ ＜ ２．６
但し、
θＩＲｐ：前記第２レンズ群に含まれる全ての正レンズの（ｎＦ－ｎｄ）／（ｎ１７００ｎｍ－ｎｄ）の平均値
θＩＲｎ：前記第２レンズ群に含まれる全ての負レンズの（ｎＦ－ｎｄ）／（ｎ１７００ｎｍ－ｎｄ）の平均値
ｎＦ：Ｆ線における屈折率
ｎｄ：ｄ線における屈折率
ｎ１７００ｎｍ：１７００ｎｍの波長における屈折率
Ｆ２：前記第２レンズ群のｄ線における焦点距離
Ｆ ：当該光学系のｄ線における焦点距離
In order to solve the above problems, the optical system according to the present invention is arranged on the image side and a first lens group having a refractive power arranged on the object side with a variable interval on the object side at the time of focusing. The first lens group is composed of a second lens group having a positive refractive power, and the first lens group includes a positive lens and at least one or more negative lenses in order from the image side, and the second lens group includes. The second group A having a positive refractive power, the aperture aperture, and the second group B having a positive refractive power are in order from the object side, and the second B group has a negative lens and a positive lens in order from the object side. It is characterized by satisfying the following conditional expression including.
(1) -0.050 <θIRp-θIRn <0.050
(2) 1.5 <F2 / F <2.6
however,
θIRp: (nF-nd) / (n1700nm-nd) average value of all positive lenses included in the second lens group θIRn: (nF-nd) / of all negative lenses included in the second lens group Average value of (n1700nm-nd) nF: Refractive index in F line nd: Refractive index in d line n1700nm: Refractive index in wavelength of 1700nm F2: Focal length in d line of the second lens group F: d of the optical system Focal length in line
また、上記課題を解決するために本件発明に係る撮像装置は、上記光学系と、当該光学系によって形成された光学像を電気的信号に変換にする撮像素子とを備えたことを特徴とする。 Further, in order to solve the above problems, the image pickup apparatus according to the present invention is characterized by including the above optical system and an image pickup element that converts an optical image formed by the optical system into an electric signal. ..
本件発明によれば、可視光域から近赤外域全域において諸収差が良好に補正された結像性能の高い光学系及び撮像装置を提供することができる。 According to the present invention, it is possible to provide an optical system and an image pickup apparatus having high imaging performance in which various aberrations are satisfactorily corrected in the entire visible light region to the near infrared region.
以下、本件発明に係る光学系及び撮像装置の実施の形態を説明する。但し、以下に説明する光学系及び撮像装置は本件発明に係る光学系及び撮像装置の一態様であって、本件発明に係る光学系及び撮像装置は以下の態様に限定されるものではない。 Hereinafter, embodiments of the optical system and the image pickup apparatus according to the present invention will be described. However, the optical system and the image pickup apparatus described below are one aspect of the optical system and the image pickup apparatus according to the present invention, and the optical system and the image pickup apparatus according to the present invention are not limited to the following aspects.
１．光学系
１－１．光学構成
当該光学系は、合焦時における最も物体側の可変間隔を挟んで、物体側に配置される屈折力を有する第１レンズ群と、像側に配置される正の屈折力を有する第２レンズ群とから構成される。さらに、当該光学系では、第１レンズ群は、像側から順に、正レンズと、少なくとも１枚以上の負レンズとを含む。また、第２レンズ群は、物体側から順に、正の屈折力を有する第２Ａ群と、開口絞りと、正の屈折力を有する第２Ｂ群とを有する。さらに、第２Ｂ群は、物体側から順に負レンズと、正レンズとを含む。このような光学構成を採用しつつ、後述する条件式を少なくとも１つ以上満足させることにより、可視光域から近赤外域まで良好に収差が補正された結像性能の高い光学系を得ることができる。
1. 1. Optical system 1-1. Optical configuration The optical system has a first lens group having a refractive power arranged on the object side and a first lens group having a positive refractive power arranged on the image side with a variable interval on the object side at the time of focusing. It consists of two lens groups. Further, in the optical system, the first lens group includes a positive lens and at least one or more negative lenses in order from the image side. Further, the second lens group has a second group A having a positive refractive power, an aperture diaphragm, and a second group B having a positive refractive power in order from the object side. Further, the second group B includes a negative lens and a positive lens in order from the object side. By satisfying at least one conditional expression described later while adopting such an optical configuration, it is possible to obtain an optical system having high imaging performance in which aberrations are well corrected from the visible light region to the near infrared region. can.
（１）第１レンズ群
第１レンズ群は、屈折力を有し、像側から順に正レンズ、負レンズの少なくとも２枚のレンズから構成されればよく、負レンズの物体側に他のレンズを備えていてもよい。例えば、第１レンズ群の最も物体側に正レンズを備える構成とすれば、広い画角を確保しつつ、歪曲収差を良好に補正することが可能になるため好ましい。第１レンズ群の屈折力の符号は正でもよく負でもよいが、広画角化を図る上では負であることがより好ましい。
(1) First lens group The first lens group has a refractive power and may be composed of at least two lenses, a positive lens and a negative lens, in order from the image side, and another lens is on the object side of the negative lens. May be provided. For example, it is preferable to provide a positive lens on the most object side of the first lens group because it is possible to satisfactorily correct distortion while ensuring a wide angle of view. The sign of the refractive power of the first lens group may be positive or negative, but it is more preferable that the sign is negative in order to widen the angle of view.
（２）第２レンズ群
第２レンズ群は、第１レンズ群の像側に、合焦時における最も物体側の可変間隔を介して配置される。ここで、合焦時に間隔が変化するレンズ間隔を「合焦時における可変間隔」と称する。「合焦時における最も物体側の可変間隔」は、当該光学系内における「合焦時における可変間隔」のうち最も物体側のものをいう。従って、第２レンズ群は、合焦時における最も物体側の可変間隔よりも像側に配置される全てのレンズを含む。
(2) Second lens group The second lens group is arranged on the image side of the first lens group via a variable interval on the most object side at the time of focusing. Here, the lens spacing in which the spacing changes during focusing is referred to as "variable spacing during focusing". The "variable interval on the most object side in focusing" means the one on the most object side among the "variable intervals in focusing" in the optical system. Therefore, the second lens group includes all lenses arranged on the image side of the variable spacing on the most object side at the time of focusing.
第２レンズ群は、物体側から順に、正の屈折力を有する第２Ａ群と、開口絞りと、正の屈折力を有する第２Ｂ群とを有すればよい。また、第２レンズ群には、「合焦時における可変間隔」が含まれていてもよく、例えば、第２Ｂ群の像側に、合焦時における可変間隔を介して正又は負の屈折力を有する他の群を１以上備えていてもよい。また、第２Ａ群と第２Ｂ群との間隔は合焦時に変化しなくてもよいし、変化してもよい。但し、合焦時における可変間隔の有無によらず、第２レンズ群を第２Ａ群及び第２Ｂ群から構成すれば、当該光学系を小型に構成することが容易になるため好ましい。 The second lens group may have a second group A having a positive refractive power, an aperture diaphragm, and a second group B having a positive refractive power in order from the object side. Further, the second lens group may include a "variable interval at the time of focusing". For example, a positive or negative refractive power is applied to the image side of the second group B via the variable interval at the time of focusing. It may have one or more other groups having. Further, the distance between the second group A and the second group B may not change at the time of focusing, or may change. However, it is preferable that the second lens group is composed of the second A group and the second B group regardless of the presence or absence of the variable interval at the time of focusing, because the optical system can be easily configured in a small size.
第２Ａ群は、全体で正の屈折力を有する限り、その具体的なレンズ構成は特に限定されるものではなく、少なくとも１枚以上の正レンズを含めばよい。また、第２Ｂ群は、全体で正の屈折力を有し、物体側から順に負レンズと、正レンズとを含むかぎり、その具体的なレンズ構成は特に限定されるものではない。 The specific lens configuration of the second group A is not particularly limited as long as it has a positive refractive power as a whole, and at least one or more positive lenses may be included. Further, the second group B has a positive refractive power as a whole, and its specific lens configuration is not particularly limited as long as it includes a negative lens and a positive lens in order from the object side.
１－２．動作
当該光学系では、１以上のレンズ群を光軸に沿って移動させることで、無限遠物体から近距離物体へ合焦する。例えば、第１レンズ群を光軸に沿って移動させることで、フォーカシングを行ってもよく、フォーカシングの際に移動させるレンズ群は特に限定されるものではない。しかしながら、当該光学系では、第２レンズ群全体を光軸に沿って移動させる、又は、第２Ａ群と第２Ｂ群とを異なる軌跡で光軸に沿って移動させることで無限遠物体から近距離物体へのフォーカシングを行うことが好ましい。第２レンズ群全体でフォーカシングを行えば、フォーカシングの際の駆動機構の構成が簡素になり、全体の小型化及び軽量化を図る上で好ましい。さらに、像側に配置される第２レンズ群全体でフォーカシングを行うことで、フォーカシングの際の諸収差の変動や画角の変動を抑制することができ、無限遠物体から近距離物体まで物***置によらず良好な結像性能を得ることができる。一方、第２Ａ群と第２Ｂ群の双方でフォーカシングを行えば、フォーカシングの際の各群の移動量を小さくすることができ、当該光学系の光軸方向の小型化を図ることがより容易になる。この場合、第２レンズ群を第２Ａ群と第２Ｂ群とから構成することにより、当該光学系の光軸方向の小型化を図ることがより容易になり、好ましい。なお、第１レンズ群はフォーカシングの際に光軸方向に固定することがより好ましい。
1-2. Operation In the optical system, one or more lens groups are moved along the optical axis to focus from an infinite object to a short-distance object. For example, focusing may be performed by moving the first lens group along the optical axis, and the lens group to be moved during focusing is not particularly limited. However, in the optical system, the entire second lens group is moved along the optical axis, or the second A group and the second B group are moved along the optical axis with different trajectories, so that the distance from the infinity object is short. It is preferable to perform focusing on the object. Focusing on the entire second lens group simplifies the configuration of the drive mechanism at the time of focusing, which is preferable for reducing the overall size and weight. Furthermore, by focusing on the entire second lens group arranged on the image side, it is possible to suppress fluctuations in various aberrations and angles of view during focusing, and the object position from an infinity object to a short-distance object. Good imaging performance can be obtained regardless of this. On the other hand, if focusing is performed in both the 2nd group A and the 2nd group B, the amount of movement of each group during focusing can be reduced, and it is easier to reduce the size of the optical system in the optical axis direction. Become. In this case, it is preferable that the second lens group is composed of the second group A and the second group B, because it becomes easier to reduce the size of the optical system in the optical axis direction. It is more preferable that the first lens group is fixed in the optical axis direction during focusing.
１－３．条件式
当該光学系は、上述した構成を採用すると共に、次に説明する条件式を少なくとも１つ以上満足することが好ましい。
1-3. Conditional expression It is preferable that the optical system adopts the above-mentioned configuration and satisfies at least one conditional expression described below.
１－３－１．条件式（１）
（１） －０．０５０ ＜ θＩＲｐ－θＩＲｎ ＜ ０．０５０
但し、
θＩＲｐ：第２レンズ群に含まれる全ての正レンズの（ｎＦ－ｎｄ）／（ｎ１７００ｎｍ－ｎｄ）の平均値
θＩＲｎ：第２レンズ群に含まれる全ての負レンズの（ｎＦ－ｎｄ）／（ｎ１７００ｎｍ－ｎｄ）の平均値
ｎＦ：Ｆ線における屈折率であり、Ｆ線は４８６．１３００ｎｍの波長の光をいう。
ｎｄ：ｄ線における屈折率であり、ｄ線は５８７．５６１８ｎｍの波長の光をいう。
ｎ１７００ｎｍ：１７００ｎｍの波長における屈折率
1-3-1. Conditional expression (1)
(1) -0.050 <θIRp-θIRn <0.050
however,
θIRp: Average value of (nF-nd) / (n1700nm-nd) of all positive lenses included in the second lens group θIRn: (nF-nd) / (n1700nm) of all negative lenses included in the second lens group -Nd) average value nF: Refractive index in the F line, and the F line means light having a wavelength of 486.1300 nm.
nd: Refractive index on the d-line, where the d-line refers to light having a wavelength of 587.5618 nm.
Refractive index at a wavelength of n1700nm: 1700nm
上記条件式（１）は、第２レンズ群に含まれる正レンズ及び負レンズの分散特性に関する式である。条件式（１）を満足させることで、可視光域から近赤外域全域において色収差を良好に補正することができ、可視光域から近赤外域全域において諸収差が良好に補正された結像性能の高い光学系を得ることができる。なお、上記条件式（１）の値は０であってもよい。 The conditional expression (1) is an expression relating to the dispersion characteristics of the positive lens and the negative lens included in the second lens group. By satisfying the conditional equation (1), chromatic aberration can be satisfactorily corrected in the entire visible light region to the near infrared region, and various aberrations can be satisfactorily corrected in the visible light region to the near infrared region. High optical system can be obtained. The value of the conditional expression (1) may be 0.
これに対して、条件式（１）の値が上限値以上になる場合、或いは、下限値以下になる場合のいずれにおいても、可視光域から近赤外域の全域で色収差を良好に補正することが困難になる。その結果、可視光域においては色収差を良好に補正することができても、近赤外域での色収差補正が不足する又は過剰になる、或いは、その逆に近赤外域では色収差を良好に補正することができても、可視光域においては色収差補正が不足する又は過剰になるなどするため好ましくない。 On the other hand, in either case where the value of the conditional expression (1) is equal to or greater than the upper limit value or equal to or less than the lower limit value, chromatic aberration should be satisfactorily corrected in the entire range from the visible light region to the near infrared region. Becomes difficult. As a result, even if the chromatic aberration can be satisfactorily corrected in the visible light region, the chromatic aberration correction in the near infrared region is insufficient or excessive, or conversely, the chromatic aberration is satisfactorily corrected in the near infrared region. Even if it can be done, it is not preferable because the chromatic aberration correction is insufficient or excessive in the visible light region.
上記効果を得る上で、条件式（１）の下限値は－０．０４０であることがより好ましく、－０．０３０であることがさらに好ましい。また、条件式（１）の上限値は０．０４０であることがより好ましく、０．０３０であることがさらに好ましい。なお、これらの好ましい下限値又は上限値を採用する場合、条件式（１）において不等号（＜）を等号付不等号（≦）に置換してもよい。他の式についても原則として同様である。また、他の式において等号付不等号（≦）を不等号（＜）に置換してもよい。 In order to obtain the above effect, the lower limit of the conditional expression (1) is more preferably −0.040, further preferably −0.030. Further, the upper limit of the conditional expression (1) is more preferably 0.040, and even more preferably 0.030. When adopting these preferable lower limit values or upper limit values, the inequality sign (<) may be replaced with the equal sign inequality sign (≦) in the conditional expression (1). The same applies to other formulas in principle. Further, in other equations, the inequality sign (≦) with an equal sign may be replaced with an inequality sign (<).
１－３－２．条件式（２）
（２） １．５０ ＜ Ｆ２／Ｆ ＜ ２．６０
但し、
Ｆ２：第２レンズ群のｄ線における焦点距離
Ｆ ：当該光学系のｄ線における焦点距離
1-3-2. Conditional expression (2)
(2) 1.50 <F2 / F <2.60
however,
F2: Focal length on the d-line of the second lens group F: Focal length on the d-line of the optical system
上記条件式（２）は、当該光学系の焦点距離に対する第２レンズ群の焦点距離の比を規定した式である。条件式（２）を満足させることで、可視光域から近赤外域全域において色収差補正を良好に行うことができ、像面湾曲、非点収差などの諸収差も良好に補正することができるため、結像性能の高い光学系を得ることがより容易になる。 The conditional expression (2) is an expression that defines the ratio of the focal length of the second lens group to the focal length of the optical system. By satisfying the conditional expression (2), chromatic aberration can be satisfactorily corrected in the entire visible light region to the near infrared region, and various aberrations such as curvature of field and astigmatism can be satisfactorily corrected. , It becomes easier to obtain an optical system with high imaging performance.
これに対して、この数値が下限値以下になると第２レンズ群の屈折力が強くなり、可視光域から近赤外域全域において、色収差や、像面湾曲、非点収差を良好に補正することが困難になり、結像性能の高い光学系を得ることが困難になる。一方、この数値が上限値以上になると第２レンズ群の屈折力が弱くなり、大口径化及び小型化を図ることが困難になる。 On the other hand, when this value is below the lower limit, the refractive power of the second lens group becomes stronger, and chromatic aberration, curvature of field, and astigmatism are satisfactorily corrected in the entire visible light region to near-infrared region. It becomes difficult to obtain an optical system having high imaging performance. On the other hand, when this value is equal to or greater than the upper limit, the refractive power of the second lens group becomes weak, and it becomes difficult to increase the diameter and reduce the size.
上記効果を得る上で、条件式（２）の下限値は１．７０であることがより好ましく、１．８５であることがさらに好ましい。また、条件式（２）の上限値は２．５０であることがより好ましく、２．４０であることがさらに好ましい。 In order to obtain the above effect, the lower limit of the conditional expression (2) is more preferably 1.70, and even more preferably 1.85. Further, the upper limit of the conditional expression (2) is more preferably 2.50 and even more preferably 2.40.
１－３－３．条件式（３）
第２Ｂ群において最も物体側に配置される負レンズは、下記の条件式を満足することが好ましい。
1-3-3. Conditional expression (3)
It is preferable that the negative lens arranged on the object side most in the second group B satisfies the following conditional expression.
（３） －０．００７＜ ０．００５５８×νｄ＿ｎ２Ｂ＋０．５３１－θｃｔ＿ｎ２Ｂ ＜ ０．０００
但し、
νｄ＿ｎ２Ｂ ：第２Ｂ群において最も物体側に配置される負レンズのｄ線におけるアッベ数
θｃｔ＿ｎ２Ｂ：前記第２Ｂ群において最も物体側に配置される負レンズのＣ線とｔ線に関する部分分散比
なお、Ｃ線からｔ線の部分分散比θｃｔは以下の式で定義されるものとする。
θｃｔ＝（ｎＣ－ｎｔ）／（ｎＦ－ｎＣ）
ｎＣ：Ｃ線における屈折率であり、Ｃ線は６５６．２８００ｎｍの光をいう。
ｎｔ：ｔ線における屈折率であり、ｔ線は１０１３．９８００ｎｍの光をいう。
(3) -0.007 <0.00558 × νd_n2B + 0.531-θct_n2B <0.000
however,
νd_n2B: Abbe number in the d line of the negative lens arranged on the object side most in the second B group θct_n2B: Partial dispersion ratio of the negative lens arranged on the object side in the second B group with respect to the C line and the t line. It is assumed that the partial dispersion ratio θct from the line to the t line is defined by the following equation.
θct = (nC-nt) / (nF-nC)
nC: Refractive index in the C line, and the C line means light having a diameter of 656.2800 nm.
nt: Refractive index in the t-line, where the t-line refers to light having a diameter of 1013.9800 nm.
上記条件式（３）は、第２Ｂ群において最も物体側に配置された負レンズの硝材を規定する式である。第２Ｂ群において最も物体側に配置された負レンズをこの条件式（３）を満足する硝材製のレンズとすることで、可視光域から近赤外光域まで色収差を良好に補正することがより容易になる。また、開口絞りの直後に配置される当該負レンズをこのような硝材製とすることで、他のレンズを当該硝材製とするよりも色収差をより効果的に補正することができる。 The conditional expression (3) is an expression that defines the glass material of the negative lens arranged on the object side most in the second group B. By using a lens made of glass material that satisfies this conditional equation (3) as the negative lens placed closest to the object in the second group B, chromatic aberration can be satisfactorily corrected from the visible light region to the near infrared light region. It will be easier. Further, by making the negative lens arranged immediately after the aperture stop made of such a glass material, chromatic aberration can be corrected more effectively than when other lenses are made of the glass material.
上記効果を得る上で、条件式（３）の下限値は－０．００６であることが好ましく、－０．００５であることがより好ましい。 In order to obtain the above effect, the lower limit of the conditional expression (3) is preferably −0.006, more preferably −0.005.
１－３－４．条件式（４）
第２Ａ群において最も物体側に配置された正レンズは、下記の条件式を満足することが好ましい。
1-3-4. Conditional expression (4)
It is preferable that the positive lens arranged on the object side most in the second group A satisfies the following conditional expression.
（４） ０．６２３ ＜ θｇＦ＿ｐ２Ａ
但し、
θｇＦ＿ｐ２Ａ：前記第２Ａ群において最も物体側に配置された正レンズのｇ線とＦ線に関する部分分散比
なお、ｇ線からＦ線の部分分散比θｇＦは以下の式で定義されるものとする。
θｇＦ＝（ｎｇ－ｎＦ）／（ｎＦ－ｎＣ）
ｎｇ：ｇ線における屈折率であり、ｇ線は４３５．８４００ｎｍの波長の光をいう。
(4) 0.623 <θgF_p2A
however,
θgF_p2A: Partial dispersion ratio of g-line and F-line of the positive lens arranged on the object side most in the second group A Note that the partial dispersion ratio θgF from g-line to F-line is defined by the following equation.
θgF = (ng-nF) / (nF-nC)
ng: The refractive index of the g-line, and the g-line refers to light having a wavelength of 435.8400 nm.
上記条件式（４）は、第２Ａ群において最も物体側に配置された正レンズの硝材を規定する式である。第２Ａ群において最も物体側に配置された正レンズをこの条件式（４）を満足する硝材製のレンズとすることで、可視光域内の波長の光のうち、特に、短波長側の波長の光について色収差を良好に補正することが可能になる。 The conditional expression (4) is an expression that defines the glass material of the positive lens arranged on the object side most in the second group A. By using a positive lens arranged on the object side most in the second group A as a lens made of a glass material that satisfies this conditional equation (4), among the light having a wavelength in the visible light region, particularly the wavelength on the short wavelength side. It becomes possible to satisfactorily correct chromatic aberration for light.
上記効果を得る上で、条件式（４）の下限値は０．６２５であることが好ましく、０．６３０であることがより好ましい。 In order to obtain the above effect, the lower limit of the conditional expression (4) is preferably 0.625, more preferably 0.630.
１－３－５．条件式（５）及び条件式（６）
第２Ｂ群に配置される正レンズに関し、以下の条件式を満足することが好ましい。
（５） ｎｄ＿ｐａｖｅ ＜１．７０
（６） νｄ＿ｐａｖｅ ＞５０
但し、
ｎｄ＿ｐａｖｅ：第２Ｂ群に配置される全ての正レンズのｄ線における屈折率の平均値
νｄ＿ｐａｖｅ：第２Ｂ群に配置される全ての正レンズのｄ線におけるアッベ数の平均値
1-3-5. Conditional expression (5) and conditional expression (6)
It is preferable that the following conditional expressions are satisfied with respect to the positive lenses arranged in the second group B.
(5) nd_pave <1.70
(6) νd_pave> 50
however,
nd_pave: average value of refractive index in d-line of all positive lenses arranged in group 2B νd_pave: average value of Abbe number in d-line of all positive lenses arranged in group 2B
上記条件式（５）は第２レンズ群に含まれる正レンズのｄ線におけるアッベ数の平均値を規定する式であり、条件式（６）は第２レンズ群に含まれる正レンズのｄ線にける屈折率の平均値を規定する式である。第２レンズ群に、条件式（５）及び条件式（６）を共に満足する硝材からなる正レンズを配置することで、第２レンズ群において正レンズにより生じる分散が大きくなり過ぎないようにすることができ、可視光域から近赤外光域まで色収差を良好に補正することができる。 The above conditional expression (5) is an expression that defines the average value of the Abbe numbers in the d-line of the positive lens included in the second lens group, and the conditional expression (6) is the d-line of the positive lens included in the second lens group. It is an equation that defines the average value of the refractive index of the lens. By arranging a positive lens made of a glass material that satisfies both the conditional equation (5) and the conditional equation (6) in the second lens group, the dispersion generated by the positive lens in the second lens group is prevented from becoming too large. It is possible to satisfactorily correct chromatic aberration from the visible light region to the near infrared light region.
上記効果を得る上で、条件式（５）の上限値は１．６７であることがより好ましい。また、条件式（６）の下限値は５５であることがより好ましく、６３であることがさらに好ましい。 In order to obtain the above effect, the upper limit of the conditional expression (5) is more preferably 1.67. Further, the lower limit of the conditional expression (6) is more preferably 55, and even more preferably 63.
１－３－６．条件式（７）及び条件式（８）
第２レンズ群は、以下の条件式を満足する負レンズを少なくとも１枚以上有することが好ましい。
1-3-6. Conditional expression (7) and conditional expression (8)
The second lens group preferably has at least one negative lens that satisfies the following conditional expression.
（７） θｃｔ ≧ ０．８００
（８） νｄ ≦ ５５
但し、
θｃｔ：前記第２レンズ群が有する負レンズのＣ線からｔ線の部分分散比
なお、Ｃ線からｔ線の部分分散比θｃｔは以下の式で定義されるものとする。
θｃｔ＝（ｎＣ－ｎｔ）／（ｎＦ－ｎＣ）
νｄ：第２レンズ群が有する負レンズのｄ線におけるアッベ数
(7) θct ≧ 0.800
(8) νd ≤ 55
however,
θct: Partial dispersion ratio of C line to t line of the negative lens of the second lens group Note that the partial dispersion ratio θct of C line to t line is defined by the following equation.
θct = (nC-nt) / (nF-nC)
νd: Abbe number on the d line of the negative lens of the second lens group
上記条件式（７）は硝材のＣ線からｔ線の分散性を規定する式であり、条件式（８）は硝材のｄ線におけるアッベ数を規定する式である。第２レンズ群が上記条件式（７）及び条件式（８）を満足する硝材からなる負レンズを有する構成とすることで、可視光域から近赤外域まで色収差を良好に補正することができる。 The conditional expression (7) is an expression that defines the dispersibility of the C-line to the t-line of the glass material, and the conditional expression (8) is an expression that defines the Abbe number in the d-line of the glass material. By configuring the second lens group to have a negative lens made of a glass material satisfying the above conditional equations (7) and (8), chromatic aberration can be satisfactorily corrected from the visible light region to the near infrared region. ..
上記効果を得る上で、条件式（７）の下限値は０．８１０であることがより好ましく、０．８１５であることがさらに好ましい。また、条件式（８）の上限値は５３であることがより好ましい。 In order to obtain the above effect, the lower limit of the conditional expression (7) is more preferably 0.810 and even more preferably 0.815. Further, it is more preferable that the upper limit value of the conditional expression (8) is 53.
１－３－７． 条件式（９）
（９） １．５０ ＜ Ｆ２Ｂ／Ｆ ＜ ２．６０
但し、
Ｆ２Ｂ：第２Ｂ群のｄ線における焦点距離
1-3-7. Conditional expression (9)
(9) 1.50 <F2B / F <2.60
however,
F2B: Focal length on the d-line of the 2nd group
上記条件式（９）は当該光学系の焦点距離に対する第２Ｂ群のｄ線における焦点距離の比を規定する式である。条件式（９）を満足させることにより、球面収差や色収差等の諸収差を良好に補正することが可能になり、可視光域から近赤外域までの広い波長領域において結像性能の高い光学系を実現することがより容易になる。 The above conditional equation (9) is an equation that defines the ratio of the focal length at the d-line of the second group B to the focal length of the optical system. By satisfying the conditional equation (9), it becomes possible to satisfactorily correct various aberrations such as spherical aberration and chromatic aberration, and an optical system having high imaging performance in a wide wavelength region from the visible light region to the near infrared region. Will be easier to achieve.
これに対して、この数値が下限値以下になると第２Ｂ群の屈折力が強くなり、諸収差、主に球面収差補正や色収差補正が過剰となり、可視光域から近赤外域の全域において結像性能の高い光学系を得ることが困難になる。一方、この数値が上限値以上になると、第２Ｂ群の屈折力が弱くなり、十分に球面収差や色収差を補正することが困難になる。 On the other hand, when this value is below the lower limit, the refractive power of Group 2B becomes stronger, and various aberrations, mainly spherical aberration correction and chromatic aberration correction, become excessive, and image formation occurs in the entire visible light region to near infrared region. It becomes difficult to obtain a high-performance optical system. On the other hand, when this value is equal to or higher than the upper limit, the refractive power of the second group B becomes weak, and it becomes difficult to sufficiently correct spherical aberration and chromatic aberration.
上記効果を得る上で、条件式（９）の下限値は１．７０であることが好ましく、１．８５であることがより好ましい。また、条件式（９）の上限値は２．５０であることが好ましく、２．４０であることがより好ましい。 In order to obtain the above effect, the lower limit of the conditional expression (9) is preferably 1.70, more preferably 1.85. The upper limit of the conditional expression (9) is preferably 2.50, more preferably 2.40.
２．撮像装置
次に、本件発明に係る撮像装置について説明する。本件発明に係る撮像装置は、上記本件発明に係る光学系と、当該光学系によって形成された光学像を電気的信号に変換する撮像素子とを備えたことを特徴とする。なお、撮像素子は光学系の像側に設けられることが好ましい。
2. 2. Image pickup device Next, the image pickup device according to the present invention will be described. The image pickup apparatus according to the present invention is characterized by comprising the above-mentioned optical system according to the present invention and an image pickup element that converts an optical image formed by the optical system into an electrical signal. The image sensor is preferably provided on the image side of the optical system.
ここで、本件発明に係る光学系は、可視光域から近赤外域までの広い波長域で良好な結像性能を有する。そのため、撮像素子として、ＣＣＤ（Ｃｈａｒｇｅ Ｃｏｕｐｌｅｄ Ｄｅｖｉｃｅ）センサやＣＭＯＳ（Ｃｏｍｐｌｅｍｅｎｔａｒｙ Ｍｅｔａｌ Ｏｘｉｄｅ Ｓｅｍｉｃｏｎｄｕｃｔｏｒ）センサ等の可視光域の波長の光線に対する感度を有する可視光域用のイメージセンサは勿論、近赤外域の波長の光線に対する感度を有するＳＷＩＲ（Ｓｈｏｒｔ Ｗａｖｅ ＩｎｆｒａＲｅｄ：短波長赤外線）センサなどを好適に用いることができる。特に、可視光域から近赤外域までの波長域全域（例えば、４００ｎｍから１７００ｎｍ）の光線に対して感度を有するイメージセンサと、本件発明に係る光学系とを用いれば、従来のように可視光用の撮像装置と、近赤外光用の撮像装置の２台の撮像装置を用いることなく、１台の撮像装置で可視光域から近赤外域までの光線により、物体の外部構造だけではなく、その内部等についてもセンシングが可能な産業用カメラを実現することができてより好ましい。但し、本件発明に係る撮像装置は、材料選別、異物検査、半導体検査等の用途に用いる産業用カメラに限らず、監視カメラ、車載カメラ、ドローン搭載用カメラ等の種々の用途の撮像装置に適用可能である。 Here, the optical system according to the present invention has good imaging performance in a wide wavelength range from the visible light region to the near infrared region. Therefore, as an image pickup element, an image sensor for the visible light region having sensitivity to light of a wavelength in the visible light region such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Sensor) sensor, as well as a wavelength in the near infrared region. A SWIR (Short Wave InfraRed) sensor or the like having sensitivity to light rays can be preferably used. In particular, if an image sensor having sensitivity to light rays in the entire wavelength range (for example, 400 nm to 1700 nm) from the visible light region to the near infrared region and the optical system according to the present invention are used, visible light is conventionally used. Not only the external structure of the object but also the external structure of the object by the light rays from the visible light region to the near infrared region with one image pickup device without using two image pickup devices, an image pickup device for near-infrared light and an image pickup device for near-infrared light. It is more preferable to realize an industrial camera capable of sensing the inside of the camera. However, the image pickup device according to the present invention is not limited to industrial cameras used for materials sorting, foreign matter inspection, semiconductor inspection, etc., but is applicable to image pickup devices for various purposes such as surveillance cameras, in-vehicle cameras, and drone-mounted cameras. It is possible.
図７は、当該撮像装置１０の構成の一例を模式的に示す図である。撮像装置１０は、撮像装置本体１と、当該撮像装置本体１に対して着脱可能な鏡筒２と、光学系２の像面ＩＰに配置された撮像素子３とを有する。鏡筒２内に上記本件発明に係る光学系及びフォーカシングの際にレンズ群を駆動するための駆動機構等が収容される。
FIG. 7 is a diagram schematically showing an example of the configuration of the
次に、実施例を示して本件発明を具体的に説明する。但し、本件発明は以下の実施例に限定されるものではない。 Next, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the following examples.
（１）光学構成
図１は、本件発明に係る実施例１の光学系の無限遠合焦時の断面図である。当該光学系は、合焦時における最も物体側の可変間隔を挟んで、物体側に負の屈折力を有する第１レンズ群Ｇ１を備え、像側に正の屈折力を有する第２レンズ群Ｇ２を備えている。第２レンズ群Ｇ２は物体側から順に正の屈折力を有する第２Ａ群Ｇ２Ａと、開口絞りＳと、正の屈折力を有する第２Ｂ群Ｇ２Ｂとを有している。当該光学系は、第２レンズ群Ｇ２全体を光軸に沿って物体側に移動させることで、無限遠物体から近距離物体へのフォーカシングを行う。なお、合焦時に第１レンズ群Ｇ１は光軸方向に固定されている。以下、各レンズ群の構成を説明する。
(1) Optical Configuration FIG. 1 is a cross-sectional view of the optical system of the first embodiment according to the present invention when focused at infinity. The optical system includes a first lens group G1 having a negative refractive power on the object side and a second lens group G2 having a positive refractive power on the image side with a variable interval on the object side at the time of focusing. It is equipped with. The second lens group G2 has a second group G2A having a positive refractive power in order from the object side, an aperture stop S, and a second group G2B having a positive refractive power. The optical system performs focusing from an infinity object to a short-distance object by moving the entire second lens group G2 toward the object along the optical axis. At the time of focusing, the first lens group G1 is fixed in the optical axis direction. Hereinafter, the configuration of each lens group will be described.
第１レンズ群Ｇ１は、物体側から順に、両凸レンズＬ１と、物体側凸形状の負メニスカスレンズＬ２と、両凹レンズＬ３と、物体側凸形状の負メニスカスレンズＬ４及び両凸レンズＬ５が接合された接合レンズとから構成されている。 In the first lens group G1, a biconvex lens L1, a negative meniscus lens L2 having a convex shape on the object side, a biconcave lens L3, a negative meniscus lens L4 having a convex shape on the object side, and a biconvex lens L5 are joined in this order from the object side. It is composed of a bonded lens.
次に、第２レンズ群Ｇ２の構成を説明する。第２Ａ群Ｇ２Ａは、物体側凸形状の正メニスカスレンズＬ６から構成される。第２Ｂ群は両凹レンズＬ７及び両凸レンズＬ８が接合された接合レンズと、両凸レンズＬ９及び物体側凹形状の負メニスカスレンズＬ１０が接合された接合レンズと、両凸レンズＬ１１及び両凹レンズＬ１２が接合された接合レンズと、両凸レンズＬ１３とから構成されている。 Next, the configuration of the second lens group G2 will be described. The second group G2A is composed of a positive meniscus lens L6 having a convex shape on the object side. In the second group B, a junction lens to which a biconcave lens L7 and a biconvex lens L8 are bonded, a junction lens to which a biconvex lens L9 and a negative meniscus lens L10 having a concave object side are bonded, and a biconvex lens L11 and a biconcave lens L12 are bonded. It is composed of a cemented lens and a biconvex lens L13.
なお、図１において、「Ｉ」は像面であり、具体的には、ＳＷＩＲセンサ、ＣＣＤセンサ、ＣＭＯＳセンサなどの撮像素子の撮像面、或いは、銀塩フィルムのフィルム面等を示す。また、ＳＷＩＲセンサは可視光域から近赤外波長域までの波長の光に対して感度を有するセンサとすることが好ましい。この点は、他の実施例で示す各レンズ断面図においても同様であるため、以後説明を省略する。 In FIG. 1, "I" is an image plane, and specifically, indicates an image pickup surface of an image pickup element such as a SWIR sensor, a CCD sensor, or a CMOS sensor, or a film surface of a silver halide film. Further, the SWIR sensor is preferably a sensor having sensitivity to light having a wavelength from the visible light region to the near infrared wavelength region. Since this point is the same in the cross-sectional views of each lens shown in the other examples, the description thereof will be omitted below.
（２）数値実施例
次に、当該光学系の具体的数値を適用した数値実施例について説明する。以下に、「レンズデータ」、「諸元表」、「レンズ群データ」を示す。また、各式の値（表１）は実施例３の後にまとめて示す。
(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. The "lens data", "specification table", and "lens group data" are shown below. The values of each equation (Table 1) are shown together after Example 3.
（レンズデータ）において、「面ＮＯ．」は物体側から数えたレンズ面の順番、「ｒ」はレンズ面の曲率半径、「ｄ」は光軸上のレンズ肉厚又は空気間隔、「Ｎｄ」はｄ線（波長λ＝５８７．５６１８ｎｍ）における屈折率、「νｄ」はｄ線におけるアッベ数、「θｇＦ」はｇ線からＦ線の部分分散比（（ｎｇ－ｎＦ）／（ｎＦ－ｎＣ））、「θＣＴ」Ｃ線からｔ線の部分分散比（（ｎＣ－ｎｔ）／（ｎＦ－ｎＣ））、「θＩＲ」は「（ｎＦ－ｎｄ）／（ｎ１７００ｎｍ－ｎｄ）」の値を示している。また、「ｄ」の欄において、「Ｄ（９）」、「Ｄ（２３）」と示すのは、当該レンズ面の光軸上の間隔が合焦時に変化する可変間隔であることを意味する。また、曲率半径の欄の「ＩＮＦ」は無限大を意味し、その面が平面であることを意味する。 In (lens data), "plane No." is the order of the lens planes counted from the object side, "r" is the radius of curvature of the lens plane, "d" is the lens wall thickness or air spacing on the optical axis, and "Nd". Is the refractive index at the d line (wavelength λ = 587.5618 nm), “νd” is the Abbe number at the d line, and “θgF” is the partial dispersion ratio from the g line to the F line ((ng-nF) / (nF-nC)). ), Partial dispersion ratio of "θCT" C line to t line ((nC-nt) / (nF-nC)), "θIR" indicates the value of "(nF-nd) / (n1700nm-nd)" There is. Further, in the column of "d", "D (9)" and "D (23)" mean that the distance on the optical axis of the lens surface is a variable distance that changes at the time of focusing. .. Further, "INF" in the column of radius of curvature means infinity, and means that the surface is a plane.
（諸元表）において、「Ｆ」は当該光学系の焦点距離、「Ｆｎｏ」はＦナンバー、「ω」は半画角、「Ｄ（９）」、「Ｄ（２３）」は上記可変間隔であり、表には無限遠物体合焦時（ＩＮＦ）及び近距離物体合焦時（物体距離０．２ｍ）におけるそれぞれの値を示している。 In the (specification table), "F" is the focal length of the optical system, "Fno" is the F number, "ω" is the half angle of view, and "D (9)" and "D (23)" are the above variable intervals. The table shows the respective values at the time of focusing on an infinity object (INF) and the time of focusing on a short-range object (object distance 0.2 m).
（レンズ群データ）は、第１レンズ群Ｇ１、第２レンズ群Ｇ２、第２Ａ群Ｇ２Ａ、第２Ｂ群Ｇ２Ｂの焦点距離を示している。 (Lens group data) shows the focal lengths of the first lens group G1, the second lens group G2, the second A group G2A, and the second B group G2B.
これらの各表における事項は他の実施例で示す各表においても同様であるため、以下では説明を省略する。 Since the matters in each of these tables are the same in each of the tables shown in other examples, the description thereof will be omitted below.
また、図２に当該光学系の無限遠合焦時の縦収差図を示す。各図に示す縦収差図は、図面に向かって左側から順に、それぞれ球面収差（ｍｍ）、非点収差（ｍｍ）、歪曲収差（％）である。球面収差図は二点鎖線が１７００ｎｍの波長の光、一点鎖線がＣ線（６５６．２８００ｎｍ）、実線がｄ線（波長５８７．５６１８ｎｍ）、短破線がＦ線（波長４８６．１３００ｎｍ）、長破線がｇ線（波長４３５．８４００ｎｍ）における球面収差をそれぞれ示す。非点収差図は縦軸が半画角（ω）、横軸がデフォーカスであり、実線がｄ線のサジタル像面を示し、破線がｄ線のメリディオナル像面をそれぞれ示す。歪曲収差図は、縦軸が半画角（ω）、横軸が歪曲収差である。これらの事項は、他の実施例において示す各収差図においても同じであるため、以下では説明を省略する。 Further, FIG. 2 shows a longitudinal aberration diagram of the optical system at infinity in focus. The longitudinal aberration diagrams shown in each figure are spherical aberration (mm), astigmatism (mm), and distortion (%), respectively, in order from the left side when facing the drawing. In the spherical aberration diagram, the two-dot chain line is light with a wavelength of 1700 nm, the one-dot chain line is C line (656.2800 nm), the solid line is d line (wavelength 587.5618 nm), the short dashed line is F line (wavelength 486.1300 nm), and the long dashed line. Indicates spherical aberration at the g-line (wavelength 435.8400 nm). In the astigmatism diagram, the vertical axis is the half angle of view (ω), the horizontal axis is the defocus, the solid line shows the sagittal image plane of the d line, and the broken line shows the meridional image plane of the d line. In the distortion diagram, the vertical axis is the half angle of view (ω) and the horizontal axis is the distortion. Since these matters are the same in each aberration diagram shown in other examples, the description thereof will be omitted below.
（レンズデータ）
面NO. r d Nd νd θgF θCT θIR
1 108.811 3.000 1.8040 46.53 0.56 0.77 -0.39
2 -446.594 0.161
3 56.597 1.400 1.4970 81.54 0.54 0.83 -0.35
4 13.272 6.082
5 -356.688 1.200 1.8929 20.36 0.64 0.65 -0.53
6 16.385 12.235
7 204.061 1.200 1.5891 61.13 0.54 0.84 -0.33
8 24.678 6.250 1.7620 40.10 0.58 0.74 -0.43
9 -31.718 D(9)
10 21.216 4.970 1.8929 20.36 0.64 0.65 -0.53
11 32.712 5.034
12(絞り) INF 3.935
13 -63.937 1.000 1.7380 32.33 0.59 0.72 -0.44
14 12.933 5.150 1.4970 81.54 0.54 0.83 -0.35
15 -24.439 0.300
16 156.901 3.850 1.4970 81.54 0.54 0.83 -0.35
17 -13.080 1.000 1.8929 20.36 0.64 0.65 -0.53
18 -31.684 0.200
19 21.061 4.930 1.5952 67.73 0.54 0.79 -0.37
20 -14.693 1.000 1.5174 52.20 0.56 0.82 -0.35
21 14.693 1.602
22 28.185 3.800 1.9037 31.34 0.60 0.70 -0.47
23 -142.857 D(23)
(Lens data)
Surface NO. Rd Nd νd θgF θCT θIR
1 108.811 3.000 1.8040 46.53 0.56 0.77 -0.39
2-446.594 0.161
3 56.597 1.400 1.4970 81.54 0.54 0.83 -0.35
4 13.272 6.082
5 -356.688 1.200 1.8929 20.36 0.64 0.65 -0.53
6 16.385 12.235
7 204.061 1.200 1.5891 61.13 0.54 0.84 -0.33
8 24.678 6.250 1.7620 40.10 0.58 0.74 -0.43
9 -31.718 D (9)
10 21.216 4.970 1.8929 20.36 0.64 0.65 -0.53
11 32.712 5.034
12 (Aperture) INF 3.935
13 -63.937 1.000 1.7380 32.33 0.59 0.72 -0.44
14 12.933 5.150 1.4970 81.54 0.54 0.83 -0.35
15 -24.439 0.300
16 156.901 3.850 1.4970 81.54 0.54 0.83 -0.35
17 -13.080 1.000 1.8929 20.36 0.64 0.65 -0.53
18 -31.684 0.200
19 21.061 4.930 1.5952 67.73 0.54 0.79 -0.37
20 -14.693 1.000 1.5174 52.20 0.56 0.82 -0.35
21 14.693 1.602
22 28.185 3.800 1.9037 31.34 0.60 0.70 -0.47
23 -142.857 D (23)
（諸元表）
INF 0.2m
F 12.000 -
Fno 1.60 -
ω 34.79 -
D(9) 2.141 1.486
D(23) 15.034 15.688
(Specification table)
INF 0.2m
F 12.000-
Fno 1.60-
ω 34.79-
D (9) 2.141 1.486
D (23) 15.034 15.688
（レンズ群データ）
F1 -302.112
F2 28.160
F2A 56.162
F2B 28.351
(Lens group data)
F1 -302.112
F2 28.160
F2A 56.162
F2B 28.351
（１）光学構成
図３は、本件発明に係る実施例２の光学系の無限遠合焦時の断面図である。当該光学系は、合焦時における最も物体側の可変間隔を挟んで、物体側に負の屈折力を有する第１レンズ群Ｇ１を備え、像側に正の屈折力を有する第２レンズ群Ｇ２を備えている。第２レンズ群は物体側から順に正の屈折力を有する第２Ａ群Ｇ２Ａと、開口絞りＳと、正の屈折力を有する第２Ｂ群Ｇ２Ｂとを有している。当該光学系は、第２レンズ群Ｇ２全体を光軸に沿って物体側に移動させることで、無限遠物体から近距離物体へのフォーカシングを行う。以下、各レンズ群の構成を説明する。
(1) Optical Configuration FIG. 3 is a cross-sectional view of the optical system of the second embodiment according to the present invention when focused at infinity. The optical system includes a first lens group G1 having a negative refractive power on the object side and a second lens group G2 having a positive refractive power on the image side with a variable interval on the object side at the time of focusing. It is equipped with. The second lens group has a second group G2A having a positive refractive power in order from the object side, an aperture stop S, and a second group G2B having a positive refractive power. The optical system performs focusing from an infinity object to a short-distance object by moving the entire second lens group G2 toward the object along the optical axis. Hereinafter, the configuration of each lens group will be described.
第１レンズ群Ｇ１は、物体側から順に、両凸レンズＬ１と、物体側凸形状の負メニスカスレンズＬ２と、両凹レンズＬ３と、両凹レンズＬ４及び両凸レンズＬ５が接合された接合レンズとから構成されている。 The first lens group G1 is composed of a biconvex lens L1, a negative meniscus lens L2 having a convex shape on the object side, a biconcave lens L3, and a junction lens to which a biconcave lens L4 and a biconvex lens L5 are joined in order from the object side. ing.
次に、第２レンズ群Ｇ２の構成を説明する。第２Ａ群Ｇ２Ａは、物体側凸形状の正メニスカスレンズＬ６から構成される。第２Ｂ群は両凹レンズＬ７及び両凸レンズＬ８が接合された接合レンズと、両凸レンズＬ９及び物体側凹形状の負メニスカスレンズＬ１０が接合された接合レンズと、両凸レンズＬ１１及び両凹レンズＬ１２が接合された接合レンズと、両凸レンズＬ１３とから構成されている。 Next, the configuration of the second lens group G2 will be described. The second group G2A is composed of a positive meniscus lens L6 having a convex shape on the object side. In the second group B, a junction lens to which a biconcave lens L7 and a biconvex lens L8 are bonded, a junction lens to which a biconvex lens L9 and a negative meniscus lens L10 having a concave object side are bonded, and a biconvex lens L11 and a biconcave lens L12 are bonded. It is composed of a cemented lens and a biconvex lens L13.
（２）数値実施例
次に、当該光学系の具体的数値を適用した数値実施例として、「レンズデータ」、「諸元表」、「レンズ群データ」を示す。また、図４に当該光学系の無限遠合焦時における縦収差図を示す。
(2) Numerical Example Next, "lens data", "specification table", and "lens group data" are shown as numerical examples to which specific numerical values of the optical system are applied. Further, FIG. 4 shows a longitudinal aberration diagram of the optical system at infinity in focus.
（レンズデータ）
面NO. r d Nd νd θgF θCT θIR
1 37.695 5.679 1.8040 46.53 0.56 0.77 -0.39
2 -3182.289 0.380
3 122.771 1.400 1.5163 64.14 0.54 0.87 -0.31
4 13.804 6.287
5 -47.382 1.200 1.9229 18.90 0.65 0.64 -0.54
6 19.501 7.665
7 -88.131 1.200 1.5163 64.14 0.54 0.87 -0.31
8 29.255 6.385 1.7995 42.22 0.57 0.75 -0.41
9 -29.201 D(9)
10 25.387 5.400 1.8929 20.36 0.64 0.65 -0.53
11 80.878 9.028
12(絞り) INF 2.625
13 -43.464 1.000 1.7380 32.33 0.59 0.72 -0.44
14 15.414 4.872 1.4970 81.54 0.54 0.83 -0.35
15 -25.594 0.400
16 200.000 4.287 1.4970 81.54 0.54 0.83 -0.35
17 -12.500 1.000 1.8929 20.36 0.64 0.65 -0.53
18 -26.107 0.200
19 42.310 5.048 1.5952 67.73 0.54 0.79 -0.37
20 -12.839 1.000 1.5174 52.20 0.56 0.82 -0.35
21 19.708 1.326
22 27.166 2.922 1.9037 31.34 0.60 0.70 -0.47
23 -141.413 D(23)
(Lens data)
Surface NO. Rd Nd νd θgF θCT θIR
1 37.695 5.679 1.8040 46.53 0.56 0.77 -0.39
2 -3182.289 0.380
3 122.771 1.400 1.5163 64.14 0.54 0.87 -0.31
4 13.804 6.287
5 -47.382 1.200 1.9229 18.90 0.65 0.64 -0.54
6 19.501 7.665
7 -88.131 1.200 1.5163 64.14 0.54 0.87 -0.31
8 29.255 6.385 1.7995 42.22 0.57 0.75 -0.41
9 -29.201 D (9)
10 25.387 5.400 1.8929 20.36 0.64 0.65 -0.53
11 80.878 9.028
12 (Aperture) INF 2.625
13 -43.464 1.000 1.7380 32.33 0.59 0.72 -0.44
14 15.414 4.872 1.4970 81.54 0.54 0.83 -0.35
15 -25.594 0.400
16 200.000 4.287 1.4970 81.54 0.54 0.83 -0.35
17 -12.500 1.000 1.8929 20.36 0.64 0.65 -0.53
18 -26.107 0.200
19 42.310 5.048 1.5952 67.73 0.54 0.79 -0.37
20 -12.839 1.000 1.5174 52.20 0.56 0.82 -0.35
21 19.708 1.326
22 27.166 2.922 1.9037 31.34 0.60 0.70 -0.47
23 -141.413 D (23)
（諸元表）
INF 0.2m
F 16.01 -
Fno 1.60 -
ω 26.86 -
D(9) 2.742 1.489
D(23) 17.790 19.043
(Specification table)
INF 0.2m
F 16.01-
Fno 1.60-
ω 26.86-
D (9) 2.742 1.489
D (23) 17.790 19.043
（レンズ群データ）
F1 -61.605
F2 29.743
F2A 39.623
F2B 29.413
(Lens group data)
F1 -61.605
F2 29.743
F2A 39.623
F2B 29.413
（１）光学構成
図５は、本件発明に係る実施例３の光学系の無限遠合焦時の断面図である。当該光学系は、合焦時における最も物体側の可変間隔を挟んで、物体側に負の屈折力を有する第１レンズ群Ｇ１を備え、像側に正の屈折力を有する第２レンズ群Ｇ２を備えている。第２レンズ群は物体側から順に正の屈折力を有する第２Ａ群と、開口絞りＳと、正の屈折力を有する第２Ｂ群Ｇ２Ｂとを有している。当該光学系は、第２Ａ群Ｇ２Ａ及び第２Ｂ群Ｇ２Ｂをそれぞれ異なる軌跡で光軸に沿って物体側に移動させることで、無限遠物体から近距離物体へのフォーカシングを行う。以下、各レンズ群の構成を説明する。
(1) Optical Configuration FIG. 5 is a cross-sectional view of the optical system of the third embodiment of the present invention when focused at infinity. The optical system includes a first lens group G1 having a negative refractive power on the object side and a second lens group G2 having a positive refractive power on the image side with a variable interval on the object side at the time of focusing. It is equipped with. The second lens group has a second group A having a positive refractive power in order from the object side, an aperture stop S, and a second group G2B having a positive refractive power. The optical system focuses the infinity object to the short-distance object by moving the second group G2A and the second group G2B to the object side along the optical axis with different trajectories. Hereinafter, the configuration of each lens group will be described.
第１レンズ群Ｇ１は、物体側から順に、両凸レンズＬ１と、物体側凸形状の負メニスカスレンズＬ２と、両凹レンズＬ３と、両凹レンズＬ４及び両凸レンズＬ５が接合された接合レンズとから構成されている。 The first lens group G1 is composed of a biconvex lens L1, a negative meniscus lens L2 having a convex shape on the object side, a biconcave lens L3, and a junction lens to which a biconcave lens L4 and a biconvex lens L5 are joined in order from the object side. ing.
次に、第２レンズ群Ｇ２の構成を説明する。第２Ａ群Ｇ２Ａは、物体側凸形状の正メニスカスレンズＬ６から構成される。第２Ｂ群Ｇ２Ｂは両凹レンズＬ７及び両凸レンズＬ８が接合された接合レンズと、両凸レンズＬ９及び物体側凹形状の負メニスカスレンズＬ１０が接合された接合レンズと、両凸レンズＬ１１及び両凹レンズＬ１２が接合された接合レンズと、両凸レンズＬ１３とから構成されている。 Next, the configuration of the second lens group G2 will be described. The second group G2A is composed of a positive meniscus lens L6 having a convex shape on the object side. In the second group B2B, a junction lens to which a biconcave lens L7 and a biconvex lens L8 are bonded, a junction lens to which a biconvex lens L9 and a negative meniscus lens L10 having a concave object side are bonded, and a biconvex lens L11 and a biconcave lens L12 are joined. It is composed of a bonded lens and a biconvex lens L13.
（２）数値実施例
次に、当該光学系の具体的数値を適用した数値実施例として、「レンズデータ」、「諸元表」、「レンズ群データ」を示す。また、図４に当該光学系の無限遠合焦時における縦収差図を示す。
(2) Numerical Example Next, "lens data", "specification table", and "lens group data" are shown as numerical examples to which specific numerical values of the optical system are applied. Further, FIG. 4 shows a longitudinal aberration diagram of the optical system at infinity in focus.
（レンズデータ）
面NO. r d Nd νd θgF θCT θIR
1 37.600 5.526 1.8040 46.53 0.56 0.77 -0.39
2 -3183.846 0.380
3 122.865 1.400 1.5163 64.14 0.54 0.87 -0.31
4 13.764 6.317
5 -47.140 1.200 1.9229 18.90 0.65 0.64 -0.54
6 19.673 7.605
7 -87.937 1.200 1.5163 64.14 0.54 0.87 -0.31
8 29.255 6.357 1.7995 42.22 0.57 0.75 -0.41
9 -29.338 D(9)
10 25.625 5.400 1.8929 20.36 0.64 0.65 -0.53
11 83.743 D(11)
12(絞り) INF 2.625
13 -42.892 1.000 1.7380 32.33 0.59 0.72 -0.44
14 15.814 4.872 1.4970 81.54 0.54 0.83 -0.35
15 -25.453 0.400
16 200.000 4.287 1.4970 81.54 0.54 0.83 -0.35
17 -12.498 1.000 1.8929 20.36 0.64 0.65 -0.53
18 -26.273 0.200
19 41.159 5.048 1.5952 67.73 0.54 0.79 -0.37
20 -12.948 1.000 1.5174 52.20 0.56 0.82 -0.35
21 19.477 1.326
22 27.026 2.922 1.9037 31.34 0.60 0.70 -0.47
23 -142.591 D(23)
(Lens data)
Surface NO. Rd Nd νd θgF θCT θIR
1 37.600 5.526 1.8040 46.53 0.56 0.77 -0.39
2 -3183.846 0.380
3 122.865 1.400 1.5163 64.14 0.54 0.87 -0.31
4 13.764 6.317
5 -47.140 1.200 1.9229 18.90 0.65 0.64 -0.54
6 19.673 7.605
7 -87.937 1.200 1.5163 64.14 0.54 0.87 -0.31
8 29.255 6.357 1.7995 42.22 0.57 0.75 -0.41
9 -29.338 D (9)
10 25.625 5.400 1.8929 20.36 0.64 0.65 -0.53
11 83.743 D (11)
12 (Aperture) INF 2.625
13 -42.892 1.000 1.7380 32.33 0.59 0.72 -0.44
14 15.814 4.872 1.4970 81.54 0.54 0.83 -0.35
15 -25.453 0.400
16 200.000 4.287 1.4970 81.54 0.54 0.83 -0.35
17 -12.498 1.000 1.8929 20.36 0.64 0.65 -0.53
18 -26.273 0.200
19 41.159 5.048 1.5952 67.73 0.54 0.79 -0.37
20 -12.948 1.000 1.5174 52.20 0.56 0.82 -0.35
21 19.477 1.326
22 27.026 2.922 1.9037 31.34 0.60 0.70 -0.47
23 -142.591 D (23)
（諸元表）
INF 0.2m
F 16.00 -
Fno 1.60 -
ω 26.86 -
D(9) 2.863 1.819
D(11) 9.155 8.920
D(23) 17.773 19.052
(Specification table)
INF 0.2m
F 16.00-
Fno 1.60-
ω 26.86-
D (9) 2.863 1.819
D (11) 9.155 8.920
D (23) 17.773 19.052
（レンズ群データ）
F1 -60.454
F2 29.768
F2A 39.617
F2B 29.346
(Lens group data)
F1 -60.454
F2 29.768
F2A 39.617
F2B 29.346
［表１］
実施例1 実施例2 実施例3
条件式(1) θIRp－θIRn 0.025 0.025 0.025
条件式(2) F2/F 2.35 1.86 1.86
条件式(3) 0.00558×νd_n2B+0.531-θct_n2B -0.004 -0.004 -0.004
条件式(4) θgF_p2A 0.639 0.639 0.639
条件式(5) n_pave 1.62 1.62 1.62
条件式(6) νd_pave 66 66 66
条件式(7) θct 0.815 0.815 0.815
条件式(8) νd 52 52 52
条件式(9) F2B/F 2.36 1.84 1.83
[Table 1]
Example 1 Example 2 Example 3
Conditional expression (1) θIRp－θIRn 0.025 0.025 0.025
Conditional expression (2) F2 / F 2.35 1.86 1.86
Conditional expression (3) 0.00558 × νd_n2B + 0.531-θct_n2B -0.004 -0.004 -0.004
Conditional expression (4) θgF_p2A 0.639 0.639 0.639
Conditional expression (5) n_pave 1.62 1.62 1.62
Conditional expression (6) νd_pave 66 66 66
Conditional expression (7) θct 0.815 0.815 0.815
Conditional expression (8) νd 52 52 52
Conditional expression (9) F2B / F 2.36 1.84 1.83
本件発明に係る光学系は、例えば、産業カメラ（ＦＡ／ＭＶ）、ビデオカメラ、デジタルカメラ、監視カメラ等の撮像素子が搭載された撮像装置の撮像光学系として好適に適用できる。 The optical system according to the present invention can be suitably applied as an image pickup optical system of an image pickup apparatus equipped with an image pickup element such as an industrial camera (FA / MV), a video camera, a digital camera, and a surveillance camera.
Ｓ ・・・開口絞り
Ｉ ・・・像面
Ｇ１ ・・・第１レンズ群
Ｇ２ ・・・第２レンズ群
Ｇ２Ａ ・・・第２Ａ群
Ｇ２Ｂ ・・・第２Ｂ群
１ ・・・撮像装置本体
２ ・・・鏡筒
３ ・・・撮像素子
１０ ・・・撮像装置
S ... Aperture aperture I ... Image plane G1 ... First lens group G2 ... Second lens group G2A ... Second A group G2B ...
Claims (9)
前記第１レンズ群は、像側から順に、正レンズと、少なくとも１枚以上の負レンズとを含み、
前記第２レンズ群は、物体側から順に、正の屈折力を有する第２Ａ群と、開口絞りと、正の屈折力を有する第２Ｂ群とを有し、
前記第２Ｂ群は、物体側から順に負レンズと、正レンズとを含み、
下記条件式を満足することを特徴とする光学系。
（１） －０．０５０ ＜ θＩＲｐ－θＩＲｎ ＜ ０．０５０
（２） １．５０ ＜ Ｆ２／Ｆ ＜ ２．６０
但し、
θＩＲｐ：前記第２レンズ群に含まれる全ての正レンズの（ｎＦ－ｎｄ）／（ｎ１７００ｎｍ－ｎｄ）の平均値
θＩＲｎ：前記第２レンズ群に含まれる全ての負レンズの（ｎＦ－ｎｄ）／（ｎ１７００ｎｍ－ｎｄ）の平均値
ｎＦ：Ｆ線における屈折率
ｎｄ：ｄ線における屈折率
ｎ１７００ｎｍ：１７００ｎｍの波長における屈折率
Ｆ２：前記第２レンズ群のｄ線における焦点距離
Ｆ ：当該光学系の無限遠合焦時のｄ線における焦点距離 It is composed of a first lens group having a refractive power arranged on the object side and a second lens group having a positive refractive power arranged on the image side with a variable interval on the object side at the time of focusing. ,
The first lens group includes a positive lens and at least one or more negative lenses in order from the image side.
The second lens group has a second group A having a positive refractive power, an aperture stop, and a second group B having a positive refractive power in order from the object side.
The second group B includes a negative lens and a positive lens in order from the object side.
An optical system characterized by satisfying the following conditional expression.
(1) -0.050 <θIRp-θIRn <0.050
(2) 1.50 <F2 / F <2.60
however,
θIRp: (nF-nd) / (n1700nm-nd) average value of all positive lenses included in the second lens group θIRn: (nF-nd) / of all negative lenses included in the second lens group Average value of (n1700nm-nd) nF: Refractive index in F line nd: Refractive index in d line n1700nm: Refractive index in wavelength of 1700nm F2: Focal length in d line of the second lens group F: Infinite of the optical system Focal length on line d when in focus
（３） －０．００７＜ ０．００５５８×νｄ＿ｎ２Ｂ＋０．５３１－θｃｔ＿ｎ２Ｂ ＜ ０．０００
但し、
νｄ＿ｎ２Ｂ ：前記第２Ｂ群において最も物体側に配置される負レンズのｄ線におけるアッベ数
θｃｔ＿ｎ２Ｂ：前記第２Ｂ群において最も物体側に配置される負レンズのＣ線とｔ線に関する部分分散比
なお、Ｃ線からｔ線の部分分散比θｃｔは以下の式で定義されるものとする。
θｃｔ＝（ｎＣ－ｎｔ）／（ｎＦ－ｎＣ）
ｎＣ：Ｃ線における屈折率
ｎｔ：ｔ線における屈折率 The optical system according to claim 1, which satisfies the following conditional expression.
(3) -0.007 <0.00558 × νd_n2B + 0.531-θct_n2B <0.000
however,
νd_n2B: Abbe number in the d line of the negative lens arranged on the object side most in the second B group θct_n2B: Partial dispersion ratio of the C line and t line of the negative lens arranged on the object side most in the second B group. It is assumed that the partial dispersion ratio θct from the C line to the t line is defined by the following equation.
θct = (nC-nt) / (nF-nC)
nC: Refractive index on C line nt: Refractive index on t line
（４） ０．６２３ ＜ θｇＦ＿ｐ２Ａ
但し、
θｇＦ＿ｐ２Ａ：前記第２Ａ群において最も物体側に配置された正レンズのｇ線とＦ線に関する部分分散比
なお、ｇ線からＦ線の部分分散比θｇＦは以下の式で定義されるものとする。
θｇＦ＝（ｎｇ－ｎＦ）／（ｎＦ－ｎＣ）
ｎｇ：ｇ線における屈折率
ｎＣ：Ｃ線における屈折率 The optical system according to claim 1 or 2, which satisfies the following conditional expression.
(4) 0.623 <θgF_p2A
however,
θgF_p2A: Partial dispersion ratio of g-line and F-line of the positive lens arranged on the object side most in the second group A Note that the partial dispersion ratio θgF from g-line to F-line is defined by the following equation.
θgF = (ng-nF) / (nF-nC)
ng: Refractive index on g-line nC: Refractive index on C-line
（５） ｎｄ＿ｐａｖｅ ＜１．７０
（６） νｄ＿ｐａｖｅ ＞５０
但し、
ｎｄ＿ｐａｖｅ：前記第２Ｂ群に配置される全ての正レンズのｄ線における屈折率の平均値
νｄ＿ｐａｖｅ：前記第２Ｂ群に配置される全ての正レンズのｄ線におけるアッベ数の平均値 The optical system according to any one of claims 1 to 3, which satisfies the following conditional expression.
(5) nd_pave <1.70
(6) νd_pave> 50
however,
nd_pave: average value of refractive index in d-line of all positive lenses arranged in the 2nd B group νd_pave: average value of Abbe number in d-line of all positive lenses arranged in the 2nd B group
（７） θｃｔ ≧ ０．８００
（８） νｄ ≦ ５５
但し、
θｃｔ：第２レンズ群が有する負レンズのＣ線からｔ線の部分分散比
なお、Ｃ線からｔ線の部分分散比θｃｔは以下の式で定義されるものとする。
θｃｔ＝（ｎＣ－ｎｔ）／（ｎＦ－ｎＣ）
νｄ：前記第２レンズ群が有する負レンズのｄ線におけるアッベ数
ｎＣ：Ｃ線における屈折率
ｎｔ：ｔ線における屈折率 The optical system according to any one of claims 1 to 4, wherein the second lens group has at least one negative lens satisfying the following conditional expression.
(7) θct ≧ 0.800
(8) νd ≤ 55
however,
θct: Partial dispersion ratio of C line to t line of the negative lens of the second lens group Note that the partial dispersion ratio θct of C line to t line is defined by the following equation.
θct = (nC-nt) / (nF-nC)
νd: Abbe number in the d line of the negative lens of the second lens group nC: Refractive index in the C line nt: Refractive index in the t line
（９） １．５０ ＜ Ｆ２Ｂ／Ｆ ＜ ２．６０
但し、
Ｆ２Ｂ：前記第２Ｂ群のｄ線における焦点距離 The optical system according to any one of claims 1 to 5, which satisfies the following conditional expression.
(9) 1.50 <F2B / F <2.60
however,
F2B: Focal length on the d-line of the second group B
The optical system according to any one of claims 1 to 8 and an image pickup element for converting an optical image formed by the optical system into an electrical signal are provided on the image side of the optical system. An image pickup device as a feature.
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